Mandela Turns 75, Still Fit, Healthy and the Dominant Figure in ANC : South Africa: But with key national elections coming next April, some leaders begin to think about his successor.

Nelson Mandela celebrated his 75th birthday a day early Saturday night with a $150-a-plate campaign fund-raiser, and although he is fit and healthy, the anniversary highlighted crucial questions of succession that face his movement as it prepares for next year’s elections.

The African National Congress, of which Mandela is president, is the most powerful anti-apartheid group in South Africa, with a vast assortment of dynamic leaders, both black and white.

But the ANC owes much of its strength to Mandela’s personal appeal, which it is depending on to win the April 27 elections as well as to lead the country during its first years of multiracial democracy. And therein lies a problem.

“Nobody in South Africa can ever replace Mandela in stature,” said Thami Mazwai, editor of Enterprise, the only magazine aimed at black business leaders in South Africa. “He’s in a class of his own.”

Tokyo Sexwale, leader of the ANC’s largest region, which includes Soweto and Johannesburg, says the presidential succession “is a very sensitive question in the ANC.”

“Mandela is still very strong, in excellent health,” Sexwale said. “It’s anybody’s guess who might replace him. But I don’t think anybody should speculate.”

Nevertheless, some ANC leaders have been thinking recently about the future of their organization after Mandela. Although Mandela has not been plagued by any serious health problems, and appears to be in good shape for a man who turns 75 today, the demands of his job are tremendous.

In the past three months alone, he visited Egypt and then crisscrossed the United States, working from sunup until well after dark each night to raise money for the ANC’s coming election campaign.

Only two days after returning to South Africa last week, Mandela was on the road again, traveling to an Orange Free State township where he danced with young children at a nursery school, met with local officials, gave a luncheon address and spoke at a rally.

In South Africa, Mandela’s days usually begin at 4 a.m. with exercises in his home, located in a formerly white suburb of Johannesburg. He is often at his office at ANC headquarters before 7 a.m. and doesn’t return home until after 6 p.m., retiring at 9:30.

A poll last week indicated Mandela was far and away the most popular leader among urban black South Africans. He was the first choice among 70% of blacks surveyed, an increase from his 65% approval rating a year before. White support for Mandela also increased, to 3% from 1%.

Mandela’s 27 1/2 years in prison, and his refusal to accept government offers to renounce violence in exchange for his freedom, have earned him the enduring admiration of the black masses. Political analysts believe he alone among black leaders has the credibility to bridge the gap between radicals and moderates in the ANC.

The two ANC leaders most often mentioned as possible successors are Cyril Ramaphosa, the ANC’s secretary general and chief negotiator, and Thabo Mbeki, the foreign affairs director. Both are political moderates with strong leadership skills who have earned grudging respect even from fearful whites.

The ANC’s youth league recently threw its support behind Mbeki, a longtime exile and son of Govan Mbeki, who was sentenced to life in prison with Mandela.

During Thabo Mbeki’s years in exile, where he worked in the ANC’s publicity department before heading foreign affairs, he was well-liked around the world.

Since his return, the 51-year-old Mbeki has kept a lower public profile, though he ran a close second to Communist Party chief Chris Hani when the ANC rank and file elected 50 members to the national executive council in 1991. (Hani was shot to death in April and a rightist has been charged as the gunman.)

Ramaphosa’s background is completely different. A former labor union leader and son of a policeman, Ramaphosa spent the difficult years of apartheid living inside the country.

He has been at the forefront of negotiations with the government, which may have cost him some support from militant ANC youth who fear their aspirations are being sold out at the bargaining table. But, like Mbeki, Ramaphosa is known for his intellect and charm.